Although known discharge units are used universally, as they are able to ensure a precise positioning of the cradle with respect to the spindle, as required by the narrow clearance, of the order of one millimeter, between spindle and core of the roll, they are, on the one hand, units dedicated to only one spindle and, on the other, rigid units from a functional point of view as they are only able to set down the picked up rolls in predefined points along the rail.
Attempts to solve the aforesaid problems have been made by replacing the cart on rails with a cart with wheels on the floor with position control. However, these carts have proved to be less than satisfactory, as the maximum positioning precision of these controlled carts is of the order of twenty millimeters and this does not allow the roll to be slipped out of the spindle without generating bending moments on the spindle or irreparable damage to the roll, or keeping the picked up rolls perfectly coaxial in the case in which a pack of rolls placed next to one another is to be discharged.